Building shadow length

How long a shadow does a 15 m high building cast if a 1-metre-long vertical rod casts a shadow of 90 cm at the same time? Include a sketch showing the similarity.

Final Answer:

x =  13.5 m

Step-by-step explanation:

$$\begin{gathered} b=15\text{m} \\ t=1\text{m} \\ y=90\text{cm}\to \text{m}=90:100\text{m}=0.9\text{m} \\ t:y=b:x \\ x=b/t\cdot y=15/1\cdot 0.9=13.5\text{m} \end{gathered}$$

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